Restart the application.
Grey Brown preview in Artistic Effect
If Artistic Effect is not working or showing a greyed-out/brown preview, try the listed options.
If the issue remains unresolved, follow the steps below:
Unchecking “Use Hardware Acceleration for rendering, playback and export” may slow down your application performance. Once you've completed Artistic workflow, re-check the above checkbox for better performance.
You may re-check the "Use Graphic Processor for improved performance" checkbox while not using the Artistic Effects feature.
If the above steps don't work, reach out to customer support for further help.